1. Field of the Invention
The present invention relates to an ultrasonic motorized stage using a linear ultrasonic motor.
2. Description of the Related Art
As microscope stages, motorized stages have been popularized as a replacement for manual stages. Their stage driving units are motorized by using a stepping motor in many cases. For example, for the motorized stage moving mechanism recited in Patent Document 1 (Japanese Laid-open Patent Publication No. 2003-114291), stage driving units, which are respectively mounted on the front surface and a side surface of a stage, enable the stage to move in the planar direction. In the microscope field, stages are required to be slightly driven in many cases. Therefore, a lot of motorized stages are also equipped with a displacement sensor to use feedback control.
In the meantime, since ultrasonic motors are small in size, have high responsiveness and can slightly drive a stage, they are used as an actuator for a stage driving unit. Ultrasonic motors operate by bouncing a sliding plate mounted on a side to be moved. Because the amount of move cannot be currently controlled without a displacement sensor, most ultrasonic motors are used along with a displacement sensor. As the displacement sensor, a sensor for optically reading a scale mounted on a side to be measured is used. The ultrasonic motor, the sliding plate, the displacement sensor and the scale are used as a stage driving unit. Development is in progress, such as improving the detection accuracy of displacement by integrating the sliding plate and the scale into one body, for example, like the stage recited in Patent Document 2 (Japanese Laid-open Patent Publication No. H11-352265).